// Copyright 2013 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "ui/app_list/search/term_break_iterator.h"

#include "base/i18n/char_iterator.h"
#include "base/logging.h"
#include "base/strings/string_util.h"
#include "third_party/icu/source/common/unicode/uchar.h"

namespace app_list {

TermBreakIterator::TermBreakIterator(const base::string16& word)
    : word_(word)
    , prev_(npos)
    , pos_(0)
    , iter_(new base::i18n::UTF16CharIterator(&word))
    , state_(STATE_START)
{
}

TermBreakIterator::~TermBreakIterator() { }

bool TermBreakIterator::Advance()
{
    // 2D matrix that defines term boundaries. Each row represents current state.
    // Each col represents new state from input char. Cells with true value
    // represents a term boundary.
    const bool kBoundary[][STATE_LAST] = {
        // START  NUMBER UPPER  LOWER  CHAR
        { false, false, false, false, false }, // START
        { false, false, true, true, true }, // NUMBER
        { false, true, false, false, true }, // UPPER
        { false, true, true, false, true }, // LOWER
        { false, true, true, true, false }, // CHAR
    };

    while (iter_->Advance()) {
        const State new_state = GetNewState(word_[iter_->array_pos()]);
        const bool is_boundary = kBoundary[state_][new_state];
        state_ = new_state;
        if (is_boundary)
            break;
    }

    prev_ = pos_;
    pos_ = iter_->array_pos();

    return prev_ != pos_ || !iter_->end();
}

const base::string16 TermBreakIterator::GetCurrentTerm() const
{
    DCHECK(prev_ != npos && pos_ != npos);
    return word_.substr(prev_, pos_ - prev_);
}

TermBreakIterator::State TermBreakIterator::GetNewState(base::char16 ch)
{
    if (base::IsAsciiDigit(ch) || ch == '.' || ch == ',')
        return STATE_NUMBER;

    const bool is_upper = !!u_isUUppercase(ch);
    const bool is_lower = !!u_isULowercase(ch);

    if (is_upper && is_lower) {
        NOTREACHED() << "Invalid state for ch=" << ch;
        return STATE_CHAR;
    }

    if (is_upper)
        return STATE_UPPER;
    if (is_lower)
        return STATE_LOWER;

    return STATE_CHAR;
}

} // namespace app_list
